CA19‑9 is a significant prognostic factor in stage III gastric cancer patients undergoing radical gastrectomy

Background Due to the great heterogeneity of gastric cancer (GC), the prognosis of patients within a stage is very different. Therefore, it is necessary to identify the high risk factors for postoperative recurrence and metastasis and take appropriate therapeutic strategies to improve the prognosis of patients. In this study, we aimed to explore the prognostic significance of preoperative and postoperative serum carcinoembryonic antigen (CEA), carbohydrate antigen 19 − 9 (CA19-9) and carbohydrate antigen 72 − 4 (CA72-4) in patients with stage I, II and III GC who underwent radical gastrectomy. Methods A total of 580 patients who underwent curative surgical resection and had not received neoadjuvant chemotherapy were included in this study. The relationship between clinicopathological features and recurrence was analysed. Survival analysis was performed by Kaplan–Meier curve. Univariate and multivariate Cox regression analyses were performed to determine prognostic factors in GC patients. Results Among patients with stage III GC, the recurrence free survival (RFS) and overall survival (OS) of patients with CA19-9>35 U/mL were significantly lower than those with CA19-9 ≤ 35 U/mL; CA19-9 was always a significant independent marker. CEA and CA72-4 were sometime useful to predict RFS or OS alternatively in the pre- or postoperative period. The only other independent significant factors for prognosis in our study were lymph node metastases for RFS and postoperative adjuvant chemotherapy for OS. Conclusion Preoperative and postoperative CA19-9 values are independent risk factors for predicting prognosis in stage III GC after curative gastrectomy. Supplementary Information The online version contains supplementary material available at 10.1186/s12893-024-02324-3.


Introduction
Gastric cancer (GC) is a heterogeneous and highly aggressive malignant tumor, and it is the fourth leading cause of cancer-related death worldwide [1].Because of its insidious onset, most GC patients are already in the advanced stage at the time of diagnosis rendening treatment difficult, with a high rate of recurrence and relatively poor prognosis [2,3].Radical gastrectomy with adjuvant chemotherapy is presently considered a standard treatment for stage II/III advanced GC patients [4].However, the prognosis of GC patients undergoing radical gastrectomy remains poor [5][6][7].Recurrence and distant metastasis are the main reason for death of GC patients after curative resection.Due to prognostic heterogeneity within each stage, identification of specific risk factors and accurate prediction for recurrence is warranted; this would help in performing appropriate intensive adjuvant therapies and in surveillance planning [8].
Serum tumor markers reflect tumor characteristics and burden generated by the tumor itself or in response to tumor cells [9,10].They have been used for GC screening and surveillance of relapse after radical surgery [11].An increase in tumor markers is usually detected before clinical recurrence.Although many studies have reported that preoperative carcinoembryonic antigen (CEA), carbohydrate antigen 19 − 9 (CA19-9) and carbohydrate antigen 72 − 4 (CA72-4) can be used as prognostic factors [12,13], their association with the prognosis and recurrence in different GC stages remains unclear.Thus, the aim of this study was to explore the prognostic significance of serum CEA, CA19-9 and CA72-4 levels for GC patients with stage I, II and III who underwent radical gastrectomy and their relationship with recurrence.

Study population
A total of 580 GC patients who underwent radical gastrectomy at the Affiliated Hospital of XuZhou Medical University and Nanjing Gaochun People , s Hospital from August 2018 to August 2021 were retrospectively enrolled in this study.A diagnosis of GC was confirmed by histopathology, and TNM stage was staged in accordance with the 8th Edition of the American Joint Committee on Cancer (AJCC) classification.The protocol was approved by the Hospital Ethics Committee, and written informed consent was signed by all patients.Exclusion criteria included: (1) patients with previous or concomitant other cancer; (2) patients with non-radical surgery or distant metastases; (3) patients with prior history of neoadjuvant therapy; and (4) patients without key clinical variables or follow-up data.

Data collection and follow-up
Clinicopathological data including sex, age, tumor location, tumor size, pathologic type, degree of differentiation, nerve and vascular invasion, lymph node status and postoperative chemotherapy were recorded.Preoperative serum CEA, CA19-9 and CA72-4 levels (< 1 weeks before surgery) were recorded.The CA19-9 value less than 1 U/mL was excluded.For patients with recurrence, postoperative tumor marker levels (> 3 months after surgery) before recurrence were recorded during follow-up.For patients without recurrence, the postoperative tumor marker levels (> 3 months after surgery) before the end of follow-up were recorded during follow-up.The normal reference values of CEA, CA19-9 and CA72-4 were 5.0ng/ml, 35 U/ml and 6.9 U/ml, respectively.A test value above normal was considered positive.The positive results were defined when CEA (+) > 5.0 ng/mL, CA19-9 (+) > 35 U/mL and CA72-4 (+) > 6.9 U/mL.During the follow-up period, recurrence was confirmed by postoperative serum tumor biomarker levels, enhanced CT, gastroscopy and other relevant examinations.Overall survival (OS) was defined as the time from the date of surgery to the date of death or the end of follow-up (August 2022), and recurrence free survival (RFS) was the time interval between the date of surgery and the date of objective tumor relapse or the end of follow-up.

Statistical analysis
Categorical variables were analysed using Pearson chisquare tests or Fisher's exact test.Kaplan-Meier survival curves were obtained by GraphPad Prism 8 software and compared with the log rank test.Univariate and multivariate analyses were performed to evaluate the independent risk factors associated with OS and PFS using the Cox proportional hazards model.The statistical analysis was performed using SPSS 26.0 (SPSS, Inc).The P value less than 0.05 was considered to be statistically significant.

Patient characteristics
A total of 580 patients underwent radical gastrectomy, including 115 patients in stage I, 163 patients in stage II, and 302 patients in stage III.Of these patients, 423 were male and 157 were female.The median age was 65 years (range 32-86 years).The median follow-up duration was 29 months (range 9-45 months), and 86 patients (14.8%) died and 97 cases (16.7%) had a tumor recurrence.
Totally 9 patients in stage I, 73 patients in stage II, and 140 patients in stage III received postoperative adjuvant chemotherapy (PAC), of whom 1, 11 and 85 patients relapsed in stage I, II and III, respectively.The PAC regimen was SOX regimen (S-1 combined with oxaliplatin).

Correlation between CEA, CA19-9 and CA72-4 levels and recurrence in GC patients with stage I, II and III
The proportions of patients with preoperative and postoperative CEA (+) and CA19-9 (+) levels were significantly higher in those at stage III and with recurrence than that in patients at stage I and II (Tables 1 and 2).In addition, The RFS values were 99.1%, 89.1% and 58.3% for patients with stage I, II and III GC, respectively (Fig. 1a).Moreover, the OS values were 98.0%, 91.5% and 62.4% for GC patients with stage I, II and III, respectively (Fig. 1b).Kaplan-Meier survival analysis revealed that GC patients with stage III had a worse prognosis than those with stage I and II (Fig. 1).Further analysis showed that stage III GC patients with high pre-or postoperative levels of CEA, CA19-9 and CA72-4 trended to have lower RFS and OS, however, this difference was not significant in stage I and II GC patients (Fig. S).Therefore, we further analyzed the role of CEA, CA19-9 and CA72-4 levels in postoperative recurrence of patients with stage III GC.

Prognostic significance of preoperative and postoperative CA19-9 levels in patients with stage III GC
Multivariate analysis had showed that preoperative and postoperative CA19-9 levels were the significantly independent factors for RFS and OS.We further analyzed the prognostic impact of preoperative and postoperative CA19-9 levels in stage III GC.The patients were categorized into the following four groups according to preoperative and postoperative CA19-9 levels: preoperative CA19-9 ≤ 35 U/mL and postoperative CA19-9 > 35 U/mL, pre-and postoperative CA19-9 > 35 U/mL, pre-and postoperative CA19-9 ≤ 35 U/mL, preoperative CA19-9 > 35 U/mL and postoperative CA19-9 ≤ 35 U/ mL.The Kaplan-Meier curves for RFS and OS in connection with CA19-9 values were shown in Fig. 2. The RFS of patients with preoperative high CA 19 -9 that become negative after surgery were longer than that of patients always above 35 U/mL (Fig. 2a, p = 0.0015).The RFS of patients always under 35 U/mL were also longer than preoperative low CA19-9 that become positive after surgery (Fig. 2a, p < 0.001).The same trend was observed for OS (Fig. 2b).Thus, the results indicated that the patients with a elevated postoperative CA19-9 level had a poor prognosis.
The RFS and OS of patients with preoperative high CA19-9 that become negative after surgery were lower than patients always under 35 U/mL (Fig. 2a-b, p = 0.0127, p < 0.001, respectively).Excluding the factor of postoperative adjuvant chemotherapy (PAC), the OS of patients with preoperative high CA19-9 was also significantly lower than that of patients with preoperative low CA19-9 (Fig. 3a-b, p = 0.0021, p = 0.0020, respectively).Thus, preoperative high CA19-9 levels also indicated poor outcomes.

Discussion
Gastric cancer (GC) is a highly heterogeneous and aggressive malignant tumor with poor prognosis.Due to prognostic heterogeneity within each stage, identification of high-risk subgroups and individualized treatment is warranted.Previous study showed that tumor markers can be used in the diagnosis, prognosis, recurrence prediction and treatment response of GC [14].They can also reflect tumor progression and burden.Therefore, this study investigated the prognostic value of serum CEA,    CA19-9 and CA72-4 levels and their relationship with recurrence in patients with stage I, II and III GC who underwent radical gastrectomy.Advanced gastric cancer patients are more likely to relapse and has a worse outcome after radical gastrectomy.Tumor markers have been reported as valuable predictors for the prognosis of gastric cancer.Our study suggested that CEA was significant only in univariate for RFS and CA72-4 was significant in univariate and multivariate for RFS at stage III GC.The only marker always significant for RFS and OS was CA19-9 that can be a useful marker for predicting outcome compared with CEA and CA72-4.
Carbohydrate antigen 19 − 9 (CA19-9), also called sialyl Lewis antigen A, has been widely used as a tumorassociated biomarker for the treatment of gastrointestinal malignancies, especially pancreatic cancer.Due to Lewis gene dysfunction or fucosyltransferase deficiency, approximately 5-10% of individuals are Lewis antigen negative, with no or low secretion of CA19-9 [15][16][17].
Therefore, we excluded GC patients with a CA19-9 value of less than 1 U/mL as in previous studies.Most previous studies only focused on the prognostic value of preoperative CA19-9 in GC.Few studies reported the value of pre-and postoperative CA19-9 in predicting prognosis and recurrence in stage III GC.A meta-analysis of 5,072 GC patients also showed that elevated serum CA19-9 was associated with poorer OS [18] as reported by many other studies [19][20][21][22] especially in stage III GC [23] or in association with pT and pN stage [24].We did not find preoperative CEA or CA72-4 levels, pT stage were independent prognostic factors for OS and RFS.However, we found that pre-and postoperative CA19-9 were significant independent prognosis factors for RFS and OS in stage III GC.
In munivariate analysis, lymph node metastasis, postoperative CA72-4 were also significant independent factors for RFS in stage III GC.Eom BW et al. reported that LN metastasis and venous invasion were independent predictors of early recurrence [25].Kang WM et al. also reported that patient age, pT stage, pN stage, Lauren histotype, lymphovascular invasion, intraoperative chemotherapy, and postoperative chemotherapy were independent predictors of early recurrence in patients with pT2-4a stage GC [26].Wakatsuki Ket al. also reported that pN ≥ 14 and preoperative CA19-9 were independent risk factors for ERec (early recurrence within 12 months) after curative gastrectomy in pStage III GC [27].A previous study of 1179 GC patients showed that pre-or postoperative CA72-4 was independently associated with shorter OS and RFS [28].Consistent with previous findings, our study also suggested that lymph node metastasis was a risk factor for recurrence in GC patients.However, in our study preoperative CA72-4 was not an independent factors for RFS and OS in stage III GC, so further study is needed.
Multivariate analysis also showed that postoperative adjuvant chemotherapy (PAC) was a significant independent protective factor for OS in stage III GC.This indicated that PAC was beneficial to the prognosis of stage III GC patients.A previous study reported that adjuvant chemotherapy can improve the survival rate and diseasefree survival rate of GC patients, and reduce the relapse rate after curative resection [29].Randomized phase III trials showed that postoperative adjuvant therapy with S-1 or S-1 plus docetaxel could improve OS and RFS in patients with stage III GC who had undergone D2 gastrectomy [30,31].In addition, stage III GC patients with preoperative high CA19-9 that become negative after surgery had longer RFS and OS, but lower than patients always under 35 U/ml.Therefore, monitor the preoperative and postoperative CA19-9 levels in stage III GC patients is of great value for evaluating the treatment effect, predicting recurrence and prognosis.Due to preoperative or postoperative high CA19-9 levels all indicated poor outcomes.Thus, intensive postoperative anticancer management should be received.
This study had a few limitations.First, this was a retrospective study from two institutions with a possible selection bias and a relatively small samples.Second, follow-up period was short, and some cases were followed up for less than 3 years.Third, the comorbidities and postoperative complications were not investigated in this study, which could also affect the prognosis.Thus, a prospective, multicentre study with longer follow-up period is urgently needed for further investigation.

Conclusions
This study showed preoperative and postoperative CA19-9 levels to be independent risk factors for predicting prognosis in stage III GC after curative gastrectomy.Patients with higher CA19-9 values should hence be considered for receiving intensive perioperative anticancer

Fig. 1
Fig. 1 RFS curves (a) and OS curves (b) of GC patients with stage I, II and III

Fig. 2
Fig. 2 Prognostic impact of pre-and postoperative CA19-9 levels in stage III GC.RFS curves (a) and OS curves (b)

Fig. 3
Fig. 3 Prognostic impact of preoperative CA19-9 levels of stage III GC patients with (a) or without (b) postoperative adjuvant chemotherapy (PAC)

Table 3
The relationship of recurrence and clinicopathological parameters in stage III GC *Indicates that the theoretical frequency of the four-cell table is less than 5, and the statistical analysis was performed using Fisher exact probability method

Table 4
Univariate and multivariate analyses of clinicopathological factors for RFS in stage III GC

Table 5
Univariate and multivariate analyses of clinicopathological factors for OS in stage III GC